U.S. patent application number 10/412389 was filed with the patent office on 2003-09-18 for liquid crystal display device and method for manufacturing the same.
Invention is credited to Kowata, Hideki, Ohta, Akihiko, Shigeeda, Akira, Shirato, Yasuyuki.
Application Number | 20030174272 10/412389 |
Document ID | / |
Family ID | 19015978 |
Filed Date | 2003-09-18 |
United States Patent
Application |
20030174272 |
Kind Code |
A1 |
Shirato, Yasuyuki ; et
al. |
September 18, 2003 |
Liquid crystal display device and method for manufacturing the
same
Abstract
With the embodiment of the present invention, a liquid crystal
display can be produced at a low cost, which employs the COG
technology, saves installation space, mounts LSIs, and, after the
LSIs are mounted, can visibly check and inspect the mounted state
thereof (that is, electrically connected states thereof) and
lighting of the image displaying portion. The liquid crystal
display is provided with a liquid crystal displaying portion 11 in
which a surface glass substrate 9 having an electrode secured
therein and a rear glass substrate 10 having a transparent
electrode opposite thereto provided therein are overlapped so that
both of the substrates 9 and 10 are opposed to each other, and
liquid crystal is sealed in pixel areas between the substrates 9
and 10; and an FPC 7 that is provided with a circuit substrate
portion 7 including a LSI 5 which is incorporated on the surface of
the glass substrate 3 having a transparent conductive electrode 2
provided therein and is connected electrically to the electrodes,
and electrically connects respective electrodes of the liquid
crystal displaying portion 11 and circuit substrate portion 6,
wherein the FPC 7 is folded over to overlap the liquid crystal
displaying portion 11 and the circuit substrate portion 6.
Inventors: |
Shirato, Yasuyuki;
(Fukushima-shi, JP) ; Kowata, Hideki;
(Fukushima-shi, JP) ; Shigeeda, Akira;
(Fukushima-shi, JP) ; Ohta, Akihiko;
(Fukushima-shi, JP) |
Correspondence
Address: |
Intellectual Property Law Group LLP
Twelfth Floor
12 South First Street
San Jose
CA
95113
US
|
Family ID: |
19015978 |
Appl. No.: |
10/412389 |
Filed: |
April 10, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10412389 |
Apr 10, 2003 |
|
|
|
PCT/JP01/11205 |
Dec 20, 2001 |
|
|
|
Current U.S.
Class: |
349/149 |
Current CPC
Class: |
G02F 1/13452
20130101 |
Class at
Publication: |
349/149 |
International
Class: |
G02F 001/1345 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 8, 2001 |
JP |
2001-174736 |
Claims
What is claimed is:
1. A liquid crystal display comprising: a liquid crystal displaying
portion in which a first substrate having a transparent pixel
electrode provided thereon and a second substrate having a
transparent opposed pixel electrode provided thereon overlap each
other so that both said electrodes are disposed so as to be opposed
to each other, and liquid crystal is sealed in a pixel area between
said first substrate and said second substrate; a circuit substrate
portion that is mounted on a surface of said hard transparent
substrate having a transparent conductive electrode provided
thereon; and is provided with integrated circuit chips connected
electrically to said transparent conductive electrode; and flexible
connecting means for electrically connecting the transparent pixel
electrode of said liquid crystal displaying portion with the
transparent conductive electrode of said circuit substrate
portion.
2. The liquid crystal display as set forth in claim 1, wherein said
liquid crystal displaying portion and said circuit substrate
portion are folded over at the middle part of said flexible
connecting means so as to overlap each other.
3. The liquid crystal display as set forth in claim 2, wherein the
surface on which the integrated circuit chips of said hard
transparent substrate is disposed so as to face said liquid crystal
displaying portion.
4. The liquid crystal display as set forth in claim 1 or 2, wherein
said flexible connecting means is any one of a flexible printed
circuit (FPC), a heat seal, a flexible flat cable (FFC) and an
anisotropic conductive rubber connector.
5. The liquid crystal display as set forth in any one of claims 1
through 4, wherein any one of either said first substrate, second
substrate and hard transparent substrate is composed of a
transparent glass plate or transparent synthetic resin plate.
6. The liquid crystal display as set forth in claim 5, wherein the
thicknesses of said first substrate, second substrate and hard
transparent substrate are the same.
7. The liquid crystal display as set forth in claim 6, wherein said
hard transparent substrate is coated with an infrared ray shielding
film at surface other than that on which the integrated circuit
chips of said substrate are mounted.
8. A method for producing a liquid crystal display in which a first
substrate having a transparent pixel electrode provided thereon and
having a sealing agent, which sections the pixel area, coated
thereon, and a second substrate, having a transparent opposed pixel
electrode provided thereon are disposed so that both said
electrodes face each other, and liquid crystal is sealed in
respective pixel areas between said first substrate and said second
substrate, thereby making a liquid crystal displaying portion;
integrated circuit chips connected electrically to a transparent
conductive electrode are mounted on the surface of the hard
transparent substrate having said transparent conductive electrode
provided thereon to make the same into a circuit substrate portion;
and the transparent conductive electrode of said circuit substrate
portion and the transparent pixel electrode of said liquid crystal
displaying portion are electrically connected to each other by
flexible connecting means; comprising the steps of: producing a
single transparent substrate having a large area, which is
constructed of a plurality of sets disposed in one or more rows
each set consisting of said first substrate portion, said hard
transparent substrate portion and said second substrate portion
arrayed in this order; overlapping the first substrate portion,
hard transparent substrate portion and second substrate portion of
said respective sets so as to be disposed in the opposite
direction, using two of said transparent substrates having a large
area; forming a liquid crystal displaying portion area having a
liquid crystal-sealed space, which is composed of the first
substrate portion, the second substrate portion and a sealing
agent, formed therein, said liquid crystal displaying portion being
disposed at the position where said overlapped two transparent
substrates having a large area are faced to each other; forming a
circuit substrate portion area in which integrated circuit chips
are mounted on the hard transparent substrate portion adjacent to
said liquid crystal displaying portion area; and obtaining a
plurality of units for producing a liquid crystal display by
cutting and separating said two transparent substrates having a
large area, in which a plurality of units producing a liquid
crystal display, consisting of said obtained liquid crystal
displaying portion area and said circuit substrate portion area are
arrayed.
9. The method for producing a liquid crystal display as set forth
in claim 8, wherein said step for cutting and separating two
overlapped transparent substrates having a large area further
comprises the step of primarily cutting and separating said
plurality of units for producing liquid crystal displays row by
row, each row having a plurality of units, respectively, and
secondarily cutting and separating one row, which is cut and
separated by said primary cutting and separating step, unit by
unit, each unit producing respective liquid crystal displays.
10. The method for producing a liquid crystal display as set forth
in claim 9, wherein liquid crystal is poured and sealed in
respective liquid crystal displaying portion areas in a plurality
of units for producing liquid crystal displays in the respective
rows in order to obtain liquid crystal displaying portions after
said primary cutting and separating step, and said secondary
cutting and separating step is carried out thereafter.
11. The method for producing a liquid crystal display as set forth
in claim 9, wherein, in order to obtain liquid crystal displaying
portions, liquid crystal is poured and sealed in liquid crystal
displaying portion areas of said units for producing liquid crystal
displays after said primary cutting and separating step or said
secondary cutting and separating step.
12. The method for producing a liquid crystal display as set forth
in claim 9, wherein integrated circuit chips connected electrically
to the transparent conductive electrode are mounted on the surface
of the hard transparent substrate portion after said secondary
cutting and separating step, and the same is made into a circuit
substrate portion.
13. The method for producing a liquid crystal display as set forth
in claim 12, wherein the liquid crystal displaying portion of the
respective units for producing liquid crystal displays, which is
provided with a circuit substrate portion incorporating integrated
circuit chips after said secondary cutting and separating step and
the circuit substrate portion are cut and separated from each
other, and thereafter, the conductive end portions from respective
electrodes of the corresponding liquid crystal display and circuit
substrate portion are electrically connected to each other by
flexible connecting means to obtain a liquid crystal display.
14. The method for producing a liquid crystal display as set forth
in claim 13, wherein said flexible connection means is any one of a
flexible printed circuit (FPC), a heat seal, a flexible flat cable
(FFC) and an anisotropic conductive rubber connector.
15. The method for producing a liquid crystal display as set forth
in any one of claims 8 through 14, wherein said first substrate,
second substrate and hard transparent substrate are composed of a
transparent glass plate or a transparent synthetic resin plate.
Description
CROSS-REFERENCE
[0001] This is a continuation of International Application
PCT/JP01/11205, with an international filing date of Dec. 20, 2001,
which is hereby incorporated by reference.
BACKROUND OF THE INVENTION
[0002] 1. Technical Field Of The Invention
[0003] The present invention relates to a liquid crystal display
and a method for producing the same.
[0004] 2. Prior Art
[0005] Conventionally, a COG (chip-on-glass) module and a COF
(chip-on-film) module have been publicly known as liquid crystal
displays.
[0006] FIG. 11 shows a configuration of a COG module (wherein FIG.
11(a) is a plan view and FIG. 11(b) is a view taken along the line
A-A of FIG. 11(a)). The COG module shown in FIG. 11 is composed of
a liquid crystal displaying portion 43 that is obtained by
overlapping a surface substrate 41 and a rear substrate 42, to each
of which conductive line (not illustrated) constituting a
transparent pixel electrode 45 is applied, and sealing liquid
crystal in pixel areas sectioned by sealing agents between the
corresponding substrates 41 and 42; and a circuit substrate portion
47 in which an LSI (IC) 46 connected electrically to the
above-described transparent pixel electrode 45 is connected to an
area in which terminals of the above-described transparent pixel
electrodes 45 is provided on the surface substrate 41 or the rear
substrate 42, and a plurality of conductive lines of these
transparent electrode 45 are integrated.
[0007] Transparent resin and transparent glass are used as the
above-described surface and rear substrates 41 and 42. However,
since, in many cases, glass is employed, areas to which the LSI 46
is connected are provided on a glass substrate. Therefore, there
may be cases where a liquid crystal display consisting of the above
liquid crystal displaying portion 43 and circuit substrate portion
47 is called a "chip-on-glass" module.
[0008] The COG module employs a flexible cable such as FPC 49 as a
cable for connection from a conductive line of the LSI 46 to the
power source (not illustrated) side.
[0009] Also, the liquid crystal display in which the COF is used is
shown in FIG. 12 (wherein FIG. 12(a) is a plan view, and FIG. 12(b)
is a sectional view taken along the line A-A in FIG. 12(a)). The
COF module is composed of a liquid crystal displaying portion 53 in
which a surface substrate 51 and a rear substrate 52 having
conductive line, which constitutes a transparent electrode, applied
thereto are, respectively, overlapped with each other, and liquid
crystal is poured and sealed in pixel areas sectioned by a sealing
agent between both of the corresponding substrates 51 and 52; and a
circuit substrate portion 59 that forms conductive lines 55 of
metallic copper, connected to conductive lines from the
corresponding liquid crystal displaying portion 53, on a circuit
substrate 57 made of synthetic resin film such as expensive
polyimide resin, etc., and connects an LSI (IC) 56, which is
connected electrically to the transparent pixel electrode of said
liquid crystal displaying portion 53, to an area in which the
above-described conductive lines 55 of metallic copper are
integrated.
[0010] The conductive lines of the LSI (IC) 56 on the
above-described circuit substrate portion 59 are configured so as
to be connected to the power source side via an anisotropic
conductive film (not illustrated), etc. However, in the
configuration shown in FIG. 12, since the LSI 56 is provided on a
synthetic resin film, the same may be called a."chip-on-film"
module.
[0011] In the liquid crystal display constructed as shown in FIG.
12, the LSI (IC) 56 is connected to the conductive lines in the
order shown in FIG. 13. First, as shown in FIG. 13(a), a copper
foil 60 is adhered to the surface of the circuit substrate 57 (FIG.
13(b)), the same is etched after a masking agent 63 is coated (FIG.
13(c)), and a pattern of copper conductive lines 55 is formed.
Next, an ACF (Anisotropic Conductive Film) 58 is adhered to the
pattern of the etched copper conductive lines 55 (FIG. 13(e)), and
the LSI (IC) 56 is thermally pressure-fitted from above the ACF 58
(FIG. 13(f)).
[0012] In the configuration of the COG module shown in FIG. 11,
since the liquid crystal displaying portion 43 and the circuit
substrate portion 47 are provided on the rear substrates 41 and 42,
the area of the circuit substrate portion 47 in which the LSI 46 of
the COG module is mounted is increased, the area occupied by the
circuit substrate portion 47 is increased in comparison with the
liquid crystal displaying portion 43 that brings about its inherent
features and functions as a liquid crystal display. Since the FPC
49 that is a flexible cable is disposed on the surface of the rear
substrate 42, the flexible property of the FPC 49 cannot be
completely displayed, and since the circuit substrate portion
(LSI-mounted part) 47 is provided on a glass substrate together
with the liquid crystal displaying portion 43, it is not possible
to fold the circuit substrate portion 47.
[0013] Also, in the configuration of the COF module, which is shown
in FIG. 12, in order to form conductive lines 55, having a minute
thickness, of non-transparent copper on the circuit substrate 57
made of polyimide resin film being a flexible film as shown in FIG.
13, the cost of producing a mask to form conductive lines, and the
cost for inspection of connecting electrically to the conductive
lines after the conductive lines are formed are incidentally
increased. In addition, since polyimide resin is expensive, and the
product cost will be accordingly increased, which cannot be ignored
as a problem.
[0014] Further, the circuit substrate 57 that is composed of copper
conductive lines 55 and a polyimide resin film is non-transparent
as shown in FIG. 13(f), and there is a shortcoming by which the
connected state between the copper conductive lines 55 and LSI 56
cannot be visibly confirmed.
[0015] Thus, since the COF module employs a number of production
steps and uses expensive materials, there are many cases where the
development costs cannot be depreciated in a case of producing
custom products in a small lot.
[0016] Also, in the COF module shown in FIG. 12, it is necessary to
prepare a photo mask to produce a circuit substrate portion 57 for
connection of the LSI 56, a metal mold for cutting the outer
profile thereof, and special tools and fixtures to fix a soft
polyimide resin film, and high initial costs are required. Also,
since expensive ultra-thin polyimide films and ultra-thin copper
foils 60 are used as the materials of the circuit substrate 57, the
unit price thereof is very expensive. In addition, since the
circuit substrate materials and circuit conductive lines are not
transparent, it is not possible to visibly check the connected
state of the LSI 56 when it is mounted on the circuit substrate
portion 57.
SUMMARY OF THE INVENTION
[0017] Therefore, it is an object of the present invention to
provide a liquid crystal display that employs the COG technology,
is able to mount LSIs in a narrow space and, after the LSIs are
mounted, to visibly check the mounted state (that is, its
electrically connected state) and the lighting of a picture
displaying portion, and a method for producing the same. Also, it
is another object of the invention to provide a liquid crystal
display that has high reliability and whose production cost is
lower, and a method for producing the same.
[0018] These objects of the invention can be achieved and solved by
the following configurations (1) and (2):
[0019] (1) A liquid crystal display comprising: a liquid crystal
displaying portion in which a first substrate having a transparent
pixel electrode provided thereon and a second substrate having a
transparent opposed pixel electrode provided thereon overlaps each
other so that both the above-described electrodes are disposed so
as to be opposed to each other, and liquid crystal is sealed in a
pixel area between the above-described first substrate and the
above-described second substrate; a hard transparent substrate
having a transparent conductive electrode provided thereon; a
circuit substrate portion that is mounted on the surface of the
above-described hard transparent substrate and is provided with
integrated circuit chips connected electrically to the
above-described transparent conductive electrode; and flexible
connecting means for electrically connecting the transparent pixel
electrode of the above-described liquid crystal displaying portion
with the transparent conductive electrode of the above-described
circuit substrate portion.
[0020] In the liquid crystal display of the COF module type, which
is a prior art and is shown in FIG. 12, the LSI 56 is bonded to the
circuit substrate 57 made of non-transparent polyimide resin film.
However, according to the above-described invention, integrated
circuit chips are bonded on a hard transparent substrate, which is
a hard material. Thus, since the integrated circuit chips are
bonded on a hard substrate, work can be facilitated, and, in
comparison with bonding of integrated circuit chips on a
non-transparent film as in the prior arts, it is possible to
visibly check the bonding conditions of the integrated circuit
chips from the surface of the hard transparent substrate at the
side where no integrated circuit chip of the transparent substrate
is mounted. Therefore, no expensive checking apparatus is required,
and this is advantageous.
[0021] In addition, in comparison with the COF module type in FIG.
12, it is possible to produce liquid crystal displays at a low cost
since the liquid crystal displays according to the invention do not
use any expensive polyimide resin.
[0022] Also, since the liquid crystal displaying portion and the
circuit substrate portion of the above-described liquid crystal
display according to the invention can be disposed so that the
middle portion of the flexible connecting means is folded over, the
liquid crystal display can be made compact.
[0023] In comparison with a liquid crystal display of COG module
type, which is shown in FIG. 11 and belongs to the prior arts,
since the circuit substrate portion can be folded over in the
above-composed liquid crystal display according to the invention,
the area occupied by the liquid crystal displaying portion in the
entire liquid crystal display can be increased.
[0024] Also, in the above-described liquid crystal display
according to the invention, it is preferable that the surface on
which integrated circuit chips of the above-described circuit
substrate portion are mounted is disposed at the position opposite
to the above-described liquid crystal displaying portion.
[0025] Where the surface on which integrated circuit chips of the
above-described circuit substrate portion are mounted is disposed
at the position opposite to the above-described liquid crystal
displaying portion, since the integrated circuit chips are not
exposed from the substrate surface, it is possible to prevent the
integrated circuit chips from being influenced by an external
impact when a liquid crystal display is set in a casing.
[0026] Further, any one of a flexible printed circuit (FPC), a heat
seal, a flexible flat cable (FFC), and an anisotropic conductive
rubber connector may be used as the above-described flexible
connecting means of the invention.
[0027] By connecting the liquid crystal displaying portion and
circuit element portion to each other via the flexible connecting
means, and causing the flexible connecting means to be folded over,
the liquid crystal display portion and circuit element portion are
caused to overlap each other, wherein a space-saving liquid crystal
display can be obtained.
[0028] The first substrate, second substrate and hard transparent
substrate of the above-described liquid crystal display according
to the invention may be made of a transparent glass plate or
transparent synthetic resin plate.
[0029] At this time, since the plate thicknesses of the first and
second substrates and the hard transparent substrate are made the
same, it is possible to obtain a number of the above-described
three substrates from a single transparent plate having a large
area, wherein the productivity thereof is made higher than in the
case where the above respective substrates are separately
produced.
[0030] Also, it is highly recommended that an infrared ray
shielding film be coated onto the surface of the hard transparent
substrate other than the portion where the above-described
integrated circuit chips are mounted. With the construction, it is
advantageous in that a liquid crystal display (for example, of a
portable device), which is used outdoors and may be exposed to
sunlight does not erroneously operate.
[0031] (2) A method for producing a liquid crystal display in which
a first substrate having a transparent pixel electrode provided
thereon and having a sealing agent, which sections the pixel area,
coated thereon, and a second substrate having a transparent opposed
pixel electrode provided thereon are disposed so that both the
above-described electrodes face each other, and liquid crystal is
sealed in respective pixel areas between the above-described first
substrate and the above-described second substrate to make the same
into a liquid crystal portion; integrated circuit chips connected
electrically to a transparent conductive electrode are mounted on
the surface of the hard transparent substrate having the
above-described transparent conductive electrode provided thereon
to make the same into a circuit substrate portion; and the
transparent conductive electrode of the above-described circuit
substrate portion and the transparent pixel electrode of the
above-described liquid crystal displaying portion are electrically
connected to each other by flexible connecting means; comprising
the steps of: producing a single transparent substrate having a!
large area, which is constructed of a plurality of sets disposed in
one or more rows each set consisting of the above-described first
substrate portion, the above-described hard transparent substrate
portion and the above-described second substrate portion arrayed in
this order; overlapping the first substrate portion, hard
transparent substrate portion and second substrate portion of the
above-described respective sets so as to be disposed in the
opposite direction, using two of the above-described transparent
substrates having a large area; forming a liquid crystal displaying
portion area having a liquid crystal-sealed space, which is
composed of the first substrate portion, the second substrate
portion and a sealing agent, formed therein, the above-described
liquid crystal displaying portion being disposed at the position
where the above-described overlapped two transparent substrates
having a large area are faced to each other; forming a circuit
substrate portion area in which integrated circuit chips are
mounted on the hard transparent substrate portion adjacent to the
above-described liquid crystal displaying portion area; and
acquiring a plurality of units for producing a liquid crystal
display by cutting and separating the above-described two
transparent substrates having a large area, in which a plurality of
units for producing a liquid crystal display, consisting of the
above-described acquired liquid crystal displaying portion area and
the above-described circuit substrate portion area are arrayed.
[0032] In the above-described method for producing a liquid crystal
display, the above-described step for cutting and separating two
overlapped transparent substrates having a large area may further
comprise the step of primarily cutting and separating the
above-described plurality of units for producing liquid crystal
displays row by row, each row having a plurality of units,
respectively, and secondarily cutting and separating one row, which
is cut and separated by the above-described primary cutting and
separating step, unit by unit, each unit being for producing
respective liquid crystal displays.
[0033] Also, liquid crystal may be poured and sealed in respective
liquid crystal displaying portion areas in a plurality of units for
producing liquid crystal displays in the respective rows in order
to obtain liquid crystal displaying portions after the
above-described primary cutting and separating step, and the
above-described secondary cutting and separating step may be
carried out thereafter.
[0034] In addition, integrated circuit chips connected electrically
to the transparent conductive electrodes are mounted on the surface
of the hard transparent substrate after the above-described
secondary cutting and separating step, thereby making the same into
a circuit substrate portion.
[0035] Still further, the liquid crystal displaying portion of the
respective units for producing liquid crystal displays, which is
provided with a circuit substrate portion incorporating integrated
circuit chips after the above-described secondary cutting and
separating step and the circuit substrate portion may be cut and
separated from each other, and thereafter, the conductive end
portions from respective electrodes of the corresponding liquid
crystal portion and circuit substrate portion may be electrically
connected to each other by a flexible connecting means to obtain a
liquid crystal display, whereby the liquid crystal displaying
portion and the circuit substrate portion may be disposed after
they are folded over via the flexible connection means and
overlapped with each other.
[0036] There are three types of shapes of transparent electrodes in
the liquid crystal display according to the invention. However,
with the method for producing the liquid crystal display according
to the invention, it is possible to produce these transparent
electrodes through a single process of photolithography by using a
single masking substrate. That is, in the prior art method, one or
two masks are required for the first and second substrates for a
liquid crystal displaying portion, and one mask that is necessary
for a circuit substrate portion is required, wherein two or three
masks are requisite in all. However, in the present invention,
using a single transparent substrate having a large area, the
above-described three types of transparent electrodes can be formed
at one time, wherein only a single mask is required. Therefore, the
exposure process and patterning process can be reduced to half or
less. In addition, where the liquid crystal display portion area
and circuit element portion area are produced with a single
transparent substrate (glass, etc.), the circuit element portion
can be produced in the same process order simultaneously as in the
process of producing a liquid crystal displaying portion
immediately before mounting the integrated chips of the circuit
element portion.
[0037] Also, the liquid crystal displaying portion area and circuit
element portion area are simultaneously produced in the same
process order by using two transparent substrates having a large
transparent substrate. After that, since the primary cutting and
separating step for cutting and separating respective rows
including a plurality of units for producing liquid crystal
displays in a line is carried out, and a plurality of units for
producing liquid crystal displays can be obtained at one time after
the primary cutting and separating process, the productivity of the
liquid crystal displays can be increased.
[0038] Also, where liquid crystal is sealed in a plurality of units
for producing liquid crystal displays after the above-described
primary cutting and separating process, it is possible to seal
liquid crystal in a number of the above-described units with a
single operation, wherein work efficiency can be increased.
[0039] Also, since it is possible to bond integrated circuit chips
onto hard transparent substrates of a plurality of units for
producing liquid crystal displays after the above-described
secondary cutting and separating step, and it is possible to easily
and securely inspect the electrical connections to the transparent
conductive electrodes on the hard transparent substrates of
integrated circuit chips, and it is possible to simultaneously
check the lighting of a plurality of liquid crystal display units
of the integrated circuit chips.
[0040] Therefore, according to the liquid crystal display of the
invention, since the LSI-mounted portion can be disposed on the
rear side of the liquid crystal displaying portion where the
circuit substrate portion is connected to the liquid crystal
displaying portion by a flexible connecting means, a compact liquid
crystal display can be obtained.
[0041] Also, according to the method for producing a liquid crystal
display of the invention, a plurality of sets of a liquid crystal
displaying portion area and a circuit substrate portion area can be
produced from a single transparent substrate having a large area,
and three types of transparent conductive lines can be produced
with a single masking substrate through a one-time photolithography
process. Also, after the liquid crystal displaying portion and
circuit element portion can be simultaneously produced by the same
process order by using two transparent substrates having a large
area, respective rows including a plurality of units for producing
liquid crystal displays in a line are, respectively, cut and
separated. After that, secondary cutting and separation are carried
out, wherein a plurality of units for producing a liquid crystal
display can be produced at one time, and productivity of the liquid
crystal displays can be increased.
[0042] Thus, material costs are made lower than that of the COF,
wherein the liquid crystal display according to the invention can
be obtained at a low cost, and since the development costs of a
liquid crystal display according to the invention are cheap, the
invention can satisfactorily meet a request for custom displays in
a small production lot.
[0043] Still further, since the LSI mounted portion (circuit
substrate portion) is transparent, the electrode thereof is
transparent, and the LSI is cemented to the transparent substrate
by a binder, the connected state of the conductive lines of the LSI
mounted portion can be visibly checked, wherein it is possible to
check the conductive-connected portion (connection portion between
the circuit substrate portion and liquid crystal portion) of the
LSI mounted portion for which yield may be the most deteriorated
during production, and a liquid crystal display having high
reliability can be obtained.
[0044] Also, in the prior art shown in FIG. 12, not only is the
circuit substrate 57 consisting of a polyimide resin film
particularly expensive, but also the workability of mounting a hard
LSI 56 onto the circuit substrate 57 made of soft polyimide resin
film is difficult. However, according to the method of the
invention, a hard. LSI 5 may be only mounted on a hard transparent
substrate 3, wherein handling of the parts can be facilitated, a
fully automated process is enabled, and the productivity thereof
can be increased.
BRIEF DESCRIPTION OF THE DRAWINGS
[0045] FIG. 1 is a perspective view of a liquid crystal display in
which the liquid crystal display according to the embodiment of the
invention is folded over at the FPC portion;
[0046] FIG. 2 is a perspective view of a COG stick substrate in
which LSI input and output conductive lines of a liquid crystal
display according to the embodiment of the invention are
formed;
[0047] FIG. 3 is a perspective view showing a circuit substrate
portion (COG stick) that is obtained by mounting LSIs on the COG
stick substrate of the liquid crystal display according to the
embodiment of the invention;
[0048] FIG. 4 is a partially sectional view showing a circuit
substrate portion in which the LSIs of a liquid crystal display
according to the embodiment of the invention are provided on a
transparent substrate, and are connected to the ACF;
[0049] FIG. 5 is a plan view showing a state during production of a
liquid crystal display for which a large glass substrate is used
during the production of the liquid crystal display according to
the embodiment of the invention;
[0050] FIG. 6(a) is a sectional view showing a state during
production of a liquid crystal display in which a large glass
substrate is used to produce the liquid crystal display according
to the embodiment of the invention, and FIG. 6(b) shows a state
where the large glass substrate is cut off and separated into the
respective units of producing the respective liquid crystal
displays.
[0051] FIG. 7(a) is a plan view showing a state of producing the
liquid crystal display for which a large glass substrata is used
according to the embodiment of the invention, and FIG. 7(b) is a
sectional view showing a state prior to cutting and separating into
respective liquid crystal displays after liquid crystal is
poured;
[0052] FIG. 8(a) is a perspective view showing a state prior to
cutting the liquid crystal displaying portion of a unit for
producing a liquid crystal display according to the embodiment of
the invention from the circuit substrate portion thereof, FIG. 8(b)
is a perspective view showing a state where LSIs are mounted on the
cut circuit substrate portion, and FIG. 8(c) is a perspective view
showing a state prior to mounting the LSIs on the circuit substrate
portion;
[0053] FIG. 91 is a perspective view showing a liquid crystal
display according to the embodiment of the invention;
[0054] FIG. 10(a) is a sectional view showing a liquid crystal
display according to the embodiment of the invention; and FIG.
10(b) is a perspective view of an anisotropic conductive rubber
connector;
[0055] FIG. 11(a) is a plan view showing a prior art COG module,
and FIG. 11(b) is a sectional view taken along the line A-A in FIG.
11(a);
[0056] FIG. 12(a) is a plan view showing a prior art COF module,
and FIG. 12(b) is a partially sectional view taken along the line
A-A in FIG. 12(a); and
[0057] FIG. 13 is a process view describing a sequence of
incorporating LSIs in a prior art COF.
DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS
[0058] A description is given of embodiments of the invention with
reference to the accompanying drawings.
[0059] As shown in FIG. 2, conductive line of a transparent
conductive electrode 2 is formed on a transparent substrate 3 by a
photolithography method, and a COG stick substrate 1 on which LSI
input and output conductive lines are formed is produced on the
transparent substrate 3 with transparent electrodes. As shown in
FIG. 3, an LSI 5 is mounted on the COG stick substrate 1 by an ACF
system described later, and a circuit substrate portion (COG stick)
6 is produced. In this connection, as shown in FIG. 9, FPC
(Flexible Print Circuits) 7 are connected to the input side
terminal of the LSI 5 of the circuit substrate portion 6.
[0060] Also, a liquid crystal displaying portion 11 is produced in
advance, in which a surface glass substrate 9 having the
transparent pixel electrode shown in FIG. 9 provided therein and a
rear glass substrate 10 having a transparent pixel electrode
opposite thereto provided therein are overlapped each other so that
both of the above-described electrodes are disposed so as to be
opposed to each other, and liquid crystal is sealed in respective
pixel areas between the above-described surface glass substrate 9
and rear glass substrate 10, and the electrode terminal and FPC 7
are connected to each other, wherein a liquid crystal display 15 is
obtained.
[0061] Further, it is preferable that a light polarizing plate is
arranged on the surface of the surface glass substrate 9, and a
flexible cable 13 for connection to the power source side is
connected to the terminal opposite to the connection portion of the
circuit substrate portion 6 with the terminal of the LSI 5.
[0062] In the liquid crystal display 15 shown in FIG. 9, since the
FPC 7 that connects the circuit substrate portion 6 and the liquid
crystal displaying portion 11 to each other can be folded over, a
compact liquid crystal display 15 can be obtained if the circuit
substrate portion 6 that is the mounted portion of the LSI 5 and
the liquid displaying portion 11 are overlapped to each other in a
state where, as shown in FIG. 1, the surface glass substrate 9 is
disposed outside.
[0063] Where the transparent conductive electrode 2 is further
formed on the corresponding glass substrate by using a transparent
glass substrate as the transparent substrate 3 of the circuit
substrate portion 6, it is possible to visibly inspect the
connected conditions between the LSI 5 and the transparent
conductive electrode 2 from the surface of the transparent
substrate 3 opposite to the LSI mounted portion by a microscope,
etc., or an image recognition device, after the LSI 5 is mounted on
the circuit substrate portion 6 via an ACF(Film consisting of the
binder 23 and the conductive beads 26).
[0064] In regard to the connection between the circuit substrate 6
and the liquid crystal displaying portion 11, a rigid connection
terminal such as a lead frame and an anisotropic conductive rubber
connector 17 shown in FIG. 10 (wherein FIG. 10(a) is a sectional
view of the liquid crystal display, and FIG. 10(b) is a perspective
view of an anisotropic conductive rubber connector) may be used
instead of using a flexible cable such as an FPC 7, etc. In the
anisotropic conductive rubber connector 17, a conductive lines 18
composed of carbon grains, silver grains, etc., is incorporated
like stripes as shown in FIG. 10(b).
[0065] Herein, FIG. 4 shows a partially sectional view of the
circuit substrate portion 6 that is provided via an ACF
(Anisotropic Conductive Film) on an ITO 21, etc., in which the LSI
5 is secured on the transparent substrate 3. Since a gold bump 22
is provided in advance on the underside of the LSI 5, the gold bump
22 is placed on the surface of the transparent substrate 3 with the
ITO 21. At this time, a binder 23 composed of an organic compound
is coated on the surface of the transparent substrate 3 with a
pattern of the ITO 21, and a number of conductive beads 26 whose
outer periphery is coated with an insulation film 25 are included
in the binder 23.
[0066] Therefore, if the LSI 5 is pressed to the transparent
substrate 3 with the ITO 21 with the gold bump 22 faced downward,
the conductive beads 26 in the organic binder 23, which are
provided right below the gold bump 22, are collapsed, wherein only
the portions in which the insulation film 25 is broken are
electrically connected to the gold bump 22.
[0067] And, there are conductive line of the transparent substrate
3 and transparent ITO 21 in the LSI-mounted portion. When the LSI 5
is mounted (not after production of the liquid crystal display 15
is completed), it becomes possible to visibly and easily inspect
the bonding conditions of the LSI 5 onto the conductive line of the
ITO 21 through the conductive lines of the above-described
transparent substrate 3 and transparent ITO 21. Also, lighting of
the liquid crystal displaying portion 11 can be simultaneously
checked at this time.
[0068] Therefore, since it is possible to check the conductive
line-connected portion of the LSI-mounted portion of the circuit
substrate portion 6, whose yield may be the most deteriorated,
before completion of products, defective articles can be excluded
early, wherein it is possible to provide a high quality liquid
crystal display having high reliability without wastefulness.
[0069] Also, in the prior art shown in FIG. 12, not only is the
circuit substrate 57 made of polyimide resin film particularly
expensive, but also it is difficult to mount a hard LSI 56 onto the
circuit substrate 57 made of soft polyimide resin film. However, in
the method according to the present invention, since only a hard
LSI 5 may be mounted on a hard transparent substrate 3, it becomes
easy to handle parts, wherein fully automated handling is enabled,
and productivity can be increased.
[0070] In addition, a liquid crystal display according to the
invention can also be produced by the following method. A glass
substrate 31 having a large area as shown in the plan view of FIG.
5 is prepared. In an example illustrated therein, the size of the
glass substrate 31 is such that, where one set consists of an area
(A) corresponding to the surface glass substrate 9 of the liquid
crystal displaying portion 11, an area (S) corresponding to the
hard transparent substrate 3 of the circuit substrate portion 6,
and an area (B) corresponding to the rear glass substrate 10 of the
liquid crystal displaying portion 11, six sets thereof that are
disposed in order can be produced.
[0071] LCD electrodes and conductive lines for electrode terminals
are formed on the respective areas (A) and (B) of the
above-described respective sets by using the ITO, etc., through the
steps of photo mask resist, exposure, development, etching, and
resist removal by a normal method. Also, LSI, etc., and electrode
conductive lines for connecting electrically are formed on the area
(S) by using ITO, etc., through the steps of photo mask resist,
exposure, development, etching, and resist removal by a normal
method.
[0072] Next, although not illustrated, a polyimide orientation film
(which is used to cause the orientation of liquid crystal to be
directed to a fixed direction) is coated, and the coated film is
subjected to an orientation treatment by a rubbing method in
compliance with a normal manner. Connecting electrically to paste
for connection of the electrodes, which is formed on the areas (A)
and (B), is printed. Thus, conductive line for forming a liquid
crystal displaying screen is formed on the substrates (A) and
(B).
[0073] In addition, in an example shown in FIG. 5, in a large glass
substrate 31, a transparent electrode has six sets each set
consisting of three areas (A), (S) and (B). However, it is possible
to produce the transparent electrode with a single mask (not
illustrated) by a single photolithography process.
[0074] Conventionally, one or two masks that are necessary for the
area (A) corresponding to the surface glass substrate 9 of the
liquid crystal displaying portion 11 and the area (B) corresponding
to the rear glass substrate 10 thereof, and one mask necessary for
the area (S) corresponding to the transparent substrate 3 for the
circuit substrate 6, two or three in total, are produced in
advance, respectively. And, exposure and patterning processes are
carried out substrate by substrate. However, with the present
invention, a single mask is prepared, wherein conductive lines of
the liquid displaying portion 11 and circuit substrate portion 6
can be produced, by using the single mask, through the one-time
exposure process and patterning process.
[0075] Next, a sealing agent 32 is coated on the area (A) by a
printing method. This is because spacing is secured, through which
liquid crystal is poured between the areas (A) and (B) that are
brought about by overlapping two glass substrates 31 and 31.
[0076] Prior to overlapping the areas (A) and (B), a number of gap
agents whose diameter is uniform to secure spacing into which the
above-described liquid crystal is poured are sprayed in the area
(A) or (B) that is placed on a worktable (not illustrated). And,
after two glass substrates 31 and 31 are overlapped so that, as
shown in the sectional view of FIG. 6(a), the order of arrangement
of the above-described areas (A), (S) and (B) are made reverse, the
sealing agent 32 is thermally hardened.
[0077] Next, the overlapped two glass substrates 31 and 31 are cut
off (primary cutting) along the line shown by X-X in FIG. 5. A
plurality of laminated plates, which are units for producing liquid
crystal displays disposed in parallel in lateral lines as shown in
FIG. 7(a), are obtained from the glass substrates 31 and 31 thus
obtained.
[0078] Liquid crystal 36 is poured from the liquid crystal pouring
portion 33 of the sealing agent of the respective units for
producing liquid crystal displays disposed in a row, which are
shown in FIG. 7(a), to spacing enclosed by the sealing agent
between the areas (A) and (B), thereby forming a liquid crystal
displaying portion 11. FIG. 7(b) shows a sectional view of the
glass substrates 31 and 31 after liquid crystal 36 is poured.
[0079] In addition, since the conductive terminal portion of the
pixel electrodes of the area (A) is formed in the area (S), the
corresponding terminal is connected to the gold bump 22 of the LSI
5 (See FIG. 4) in order to obtain a circuit substrate portion
6.
[0080] After that, where the liquid crystal displaying portion 11
and the circuit substrate portion 6 are cut off and separated
(secondary cutting) at the position shown by the arrow markings in
FIG. 6(b) and FIG. 7(b), the liquid crystal displaying portion 11
(corresponding to the areas (A) and (B)) and the circuit substrate
portion 6 (corresponding to the area (S)) are separated so as to be
integrated, wherein four liquid crystal displays 15 can be produced
at one time.
[0081] Further, as shown in FIG. 8(a), the liquid crystal
displaying portion 11 and the circuit substrate portion 6 are cut
off at the position shown with the dashed line X (FIG. 8(b)). Also,
it is described that the LSI 5 is mounted after the above-described
secondary cutting. However, where the liquid crystal displaying
portion 11 and the circuit substrate portion 6 are cut off at the
position shown with the dotted line X after the secondary cutting
(see FIG. 8(c)), herein, the LSI 5 may be mounted on the circuit
substrate portion 6.
[0082] Herein, where the LSI 5 is mounted on the circuit substrate
portion 6, checking of the lighting of the liquid crystal
displaying portion 11 and inspection of connecting electrically to
the LSI 5 of a COG stick substrate (circuit substrate portion 6)
are separately carried out.
[0083] Next, as shown in a perspective view of the liquid crystal
display 15 in FIG. 9, the liquid crystal displaying portion 11 and
the circuit substrate 6 are connected to each other by the FPC
7.
[0084] Still further, as shown in a perspective view of the liquid
crystal display 15 in FIG. 1, by bending the FPC 7 so that the
surface glass substrate 9 is disposed outside, a compact liquid
crystal display 15 can be obtained.
[0085] By coating an infrared ray shielding film (not illustrated)
on the surface other than the mounted portion of the LSI 5 of the
transparent substrate 3 of the circuit substrate portion 6, a
portable device that can be used outdoors, and a device that is
exposed to sunlight when being used can be prevented from being
subjected to any erroneous operation. For example, a tin oxide or
indium tin oxide (ITO) film is coated so that its thickness becomes
20 ohms per square meter or less, whereby the transmissivity at a
wavelength area of 830 nm is made into 20% or less, and the
irradiation intensity of infrared rays to the LSI 5 can be
decreased.
* * * * *